Difficulty seeing foresight when over target- AP60

[joecon]

Hi.
I shoot air pistol & use a sub 6 hold. When dry firing & shooting on a reduced (3.3m) range I can achieve a reasonable focus on the foresight while aiming on wall/ target. Both of these would have lighting levels akin to ‘normal domestic’ levels at the target & firing point (lower than regulation at target).
On our club's 10m range & one other I have used a number of times I have a problem where I find I can not get a focus on the foresight when the sight is over the target card. When above or below the target I can get a reasonable focus on the foresight, but as soon as the sights are on the target the foresight becomes shadowy & indistinct with its position in the rear sight difficult to gauge. Without a target card in position (on club range) aiming at target backing (green coloured plate) I can get the focus; seems like the additional light from the manila target card causes the problem?
The lighting levels on club range would be at the lower end of regulation levels on the target & firing point.

My optical condition; For driving & distance I use glasses with a -0.75 prescription (for last 15 years), by 'normal' (non shooting optician) eye exam & confirmed by my own trials I use a -0.25 lens for shooting. In most recent eye exam I got my first reading glasses at +1.5.

I know it is difficult to diagnose the problem remotely, but any suggestions as to cause or solution would be appreciated.
Joe.

[deadeyedick]

It sure is difficult to diagnose joecon, but a good idea would be to check your lens prescription . Optomoterists . have a selection of every lens strength, so re check to find the clearest sight picture. Then again, as Fred and Tenex have suggested, an iris could be the answer, however you said that the light levels at the range were at the lower end od acceptable, and my experience with an iris was that more benefit was gained in brighter, not lower light.

[tenex]

Hi Joe,
I've had problems with certain ranges when the target is on the bright side. For me, an adjustable aperture works the best for reducing the inevitable glare. I'm using a +0.75 diopter lens over my distance prescription, but I've tried others. If I understand your post, you are using +0.5 over your distance prescription?

If I have a hard time at a particular range, I just adjust the aperture to get the maximum sharpness of the sights. Sometimes this makes the target pretty clear (which I think is ok, it's the sights that matter).

I've also turned on the port light (probably makes my pupil constrict).

If you're not using an aperture you might want to give one a try, it does a good job for me.

Good shooting,
Steve.

[Fred Mannis]

Joe,
I have also experienced this problem with brightly lit targets. Like Steve, I have found that using an iris and increasing the lighting on my front sight can help. But I have found the most effective remedy to be using a very light grey tint in my lens, which is +0.75 diopter greater than my normal distance prescription.

Not clear from your description that the problem is simply lighting. Do you get the same blurring of the front sight when looking at the back (blank) side of the target card? I'm wondering whether part of your problem is that your focus is drifting to the bull.

[ausdiver99]

I have a similar problem with my latest lens, it was fine in the brightish lights of the opticians but I have found it hard to hold focus on the range during a match.

I tested the focal length with some small font print bluetacked to a wall in the range. Some moving back and forward with the glasses on (but without a gun) quickly showed where the clearest view was & a tape confirmed the focal length is wrong, for both my .22 SA and my 50 metre pistol. I thought I had it perfect for the small sights on the Toz!

I can focus initially, but my eye gets tired quickly and the focus soon drifts.

Back to shooting optics I go!

[Spencer]

Few lens suppliers will guarantee a lens to be within 1/8 dioptre, and some consider +/- 1/4 dioptre near enough.
A wise move is to have your optician verify the script of the lens before it is ground to fit you glasses/lens holder - if it ain't right, send it back.

The light levels at the optician's shop is unlikely to be anywhere near as bright as most outdoor ranges on an average day. More of a factor is the time spent looking at the distance: a few seconds at the opticians is one thing, minutes+ focussing on/at the front sight is altogether different.

Spencer

[joecon]

Deadeyedick; My shooting (intermediate) prescription was checked again only last week by a regular optician exam & again it was -0.25.

While using an iris might reduce the glare will it also reduce the light from foresight & reduce the visibility of the foresight? This may be something that needs balancing.

Steve; Yes I’m using +0.5 over my distance prescription.
‘port light’ not sure what you mean here.
I don’t have access to a variable iris to try, but maybe I can try some different sized fixed apertures – what approx sizes of apertures may be worth trying?

Fred; I have not tried the rear of the target, & I suppose it could be focus shifting to bull. I only have access to club range once a week (Sunday) so I’ll try next time. Next Sunday I have a competition (a qualifier for Intershoot 09) at the other range where I have had the same problem. Will look at trying some sort of grey/ coloured filter to see if this improves situation.
Thanks All.

[jacques b gros]

In our club, here in the boondoks of Brasil, I changed the incandescent target lamps into fluorescent. Took care of choosing lamps with equivalent wattages (15W fluorescent = 60W incandescent, according to the package). The reason for the change was economy, since 30 shooting posts used 1,800W only in the target lighting. (it's been a very long time sice we had more than 15 shooters. 10 is the usual.).

The unexpected result was that the target/sight picture became clearer, sharper. One shooter complained that he was going farther into the black and that our range is different from the others in Brasil. Offered him a small screw driver to adjust the sights of his Morini... ;-).

It is a lot easier to see the sights. Another range (in another state) is removing the spotlights over the targes and substituting by a ceilling line near them, as seen somewhere else. Let's wait for the results.

[joecon]

Hi. I was able to spend some time on range trying to work on the problem.
Re-checked what problem was & found that I could get good foresight focus; but when achieving this the view of the rear sight deteriorated greatly (appeared as if target was bleeding into rearsight) see 1st image; 2nd image a good sight picture.
Using lux meter rechecked light levels at bench top, rear/ foresight position & target face. All were at similar levels to that when last checked i.e. 360, 1300, 1520 lux & above min. in spec..
Aiming on reverse of target also gave same problem.
Re-verified that my -0.25 shooting glass prescription (a +0.5 overall; uncorrected is +0.75), was the best by trying 0.25 above & below it.
I had a limited number of filter substitutes of different colours & tint levels, of these a yellow & a very light gray gave the best results. The improvements were not enough to give a satisfactory sight picture.
Using various sized holes is some plastic tried to simulate an Iris, found this made a marginal improvement but also made it harder to keep focus of foresight (target was much clearer).

After this lack of success I restarted consideration of problem- as my eyesight had apparently not changed, something must! Then I thought of the shade on the over head lighting, this was put in place 4-5 weeks ago to reduce glare on our eyes. I removed the shade (cardboard sheet) & hey presto rear & foresight were clearly visible with no distortions. I retested the light levels at bench top & pistol with the shade removed & they were approximately the same as with the shade in place. I then measured light at my eye position; with shade it was 70 without it it was 330lux.
It would appear that due to the low level of light at the eye the pupil opened up to a point which caused the dept of field to be so reduced that I could not get fore & rear sight in reasonable focus. While the range specification only indicates a level for the bench (300 lux), I guess it would assume that the level at the eye would be the same or higher.


Re-searching the forum I have found a post by Albert B (at end of topic) which seems to confirm this analysis of the problem. http://www.targettalk.org/viewtopic.php ... =low+light

We also visited the other range (in Dublin) yesterday & lux measurements at the firing point were between 48 & 100 lux. This range is primarily used for air rifle (young people) so I guess the level of ambient light at firing point is not so critical. For pistol shooters & especially older ones (me) these levels would not be conducive to good scores.

Steve, I guess this is the effect you alluded to in ‘I've also turned on the port light (probably makes my pupil constrict)’.
My thanks to all for suggestions which helped to get to this point.
Joe.

[David Levene]

We also visited the other range (in Dublin) yesterday & lux measurements at the firing point were between 48 & 100 lux. This range is primarily used for air rifle (young people) so I guess the level of ambient light at firing point is not so critical. For pistol shooters & especially older ones (me) these levels would not be conducive to good scores.

I presume you are aware of ISSF rule 6.3.15.4 (and its sub-rules) which state that the minimum general range illumination should be 300 lux. At the firing point this is measured by placing the meter, facing upwards, on the 0.7m-0.8m high shooting bench.

This applies to air rifle as well as air pistol.

[jimsoars]

I too was experiencing difficulty getting a sharp sight picture. I experimented with apertures and lenses and nothing really helped. Then this thread gave me an idea...

My daughter gave me a nice LL Bean cap for Xmas. It has 2 bright LEDs in the brim that I can turn on and they point aproximately where I look. I decided to try to wear this cap while shooting in my basement. It made a great difference in my perception of the sights, they were much clearer than without the lights from the cap.

Given that this seems to work for me... would it be legal? Are there any rules that would prohibit a lighted cap?

Jim

[David Levene]

Given that this seems to work for me... would it be legal? Are there any rules that would prohibit a lighted cap?

If the range is lit in accordance with ISSF rules then I doubt you would find any benefit. If it isn't then you would have to ask the organisers how far they are prepared to deviate from the rules. If they are offering a sub-standard range then they might be prepared to allow anything.

IMHO, using personal lighting on an air range would be in breach of the part of 6.3.15.4 which says " The entire area must be evenly illuminated with no less than 300 lux." If you are adding additional lighting then you are altering the even illumination.

[Spencer]

...Given that this seems to work for me... would it be legal? Are there any rules that would prohibit a lighted cap?
Jim

- 8.4.1.1. The range conditions are the range conditions, it is not for the competitor/s to change them to suit their individual whims.
- and probably 8.6.7 as aoon as an adjoining shooter became distracted.

Sigh!
This one comes around every 20 years or so.

Spencer

[Guest]

Jim, If the light level on your sights front &/or rear is low then probably the ambient light to which the eye is exposed will be low also. My experience above has shown that it is possible to have a very will lit fore & rear sight (which your cap light may give you- legality aside) but if the eye is not getting an appropiate level of light from the rest of your area of view, then it will open up & you will find your dept of field reduced, making it difficult to see both fore & rear sights with enough clarity.
I think this is something anyone with a home range that uses point/ spot lighting would want to consider. Joe.

[joecon]

Did not notice I was not logged on 8-(

Jim, If the light level on your sights front &/or rear is low then probably the ambient light to which the eye is exposed will be low also. My experience above has shown that it is possible to have a very will lit fore & rear sight (which your cap light may give you- legality aside) but if the eye is not getting an appropiate level of light from the rest of your area of view, then it will open up & you will find your dept of field reduced, making it difficult to see both fore & rear sights with enough clarity.
I think this is something anyone with a home range that uses point/ spot lighting would want to consider. Joe.

[tleddy]

Oddly enough, the "Bad" sight picture is more typical (and desirable).

The eye has a pretty simple lens system, basically an adjustable spherical lens, and the focus happens only on the flat plane where the spherical lens is set (focused) by the ciliary muscles.

Depth of field is controlled by the diameter of the eye's iris which is very light sensitive. In bright light the iris diameter shrinks and gives a deeper depth of field than in dim light when it wide open.

There are a lot of writings on this site and Bullseye-L on optics, especially by Dr. Norman Wong, a Master shooter and optometrist. I suggest that one read those articles for an excellent, in-depth overview of the seeing process.

Tillman

[Richard H]

Given that this seems to work for me... would it be legal? Are there any rules that would prohibit a lighted cap?

If the range is lit in accordance with ISSF rules then I doubt you would find any benefit. If it isn't then you would have to ask the organisers how far they are prepared to deviate from the rules. If they are offering a sub-standard range then they might be prepared to allow anything.

IMHO, using personal lighting on an air range would be in breach of the part of 6.3.15.4 which says " The entire area must be evenly illuminated with no less than 300 lux." If you are adding additional lighting then you are altering the even illumination.

There are many ranges, probably the majority that don't meet all the ISSF criteria, just because they pass a rule doesn't mean everyone is going to rebuild their range.

Unless you're running a World Cup the range will be what it is.

The hat with the lights is definitely a no no, especially when you turn your head and shine them in someone else's eyes, but hey if it works in your basement knock yourself out.

[RobStubbs]

The hat with the lights is definitely a no no, especially when you turn your head and shine them in someone else's eyes, but hey if it works in your basement knock yourself out.

That's fine if you only ever plan to shoot in your basement and nowhere else. If you do plan shooting comps elsewhere then bin the hat. Train for the competition environment you will be in and not what you have now.

Rob.